John J. Clarke came to the Miramichi in 1881 with a 1st class teacher's license and two and a half years of teaching experience. He served for one year as principal of the five-classroom school on Wellington Street in Chatham and then for eighteen years as principal of the two-classroom superior school at Millerton, doing what the school inspector described as "very efficient work, in a very undemonstrative manner."

Clarke irritated his colleagues in 1894 when he did not appear as scheduled to present an opening paper at the annual meeting of the Teachers' Institute, and he soured relations even more when he was absent again the next year. His strengths as an educator were respected by all, however, and his resignation and withdrawal from the profession in 1900 was spoken of as "a great loss." He was one of many able men teachers of his time to leave the classroom to enter the more lucrative insurance field. He was the agent at Millerton for a national insurance company in 1901 and was later a Sun Life Co. inspector for the northern counties of New Brunswick. He stayed with the business for the rest of his working life.

Clarke's wife, Annie Henderson, predeceased him in 1936. When he died in 1939, at age eighty-three, he was survived by five daughters and a son. A grandson, Frank H. Clarke Jr, who grew up at Millerton, earned a PhD in chemistry at Harvard University and had a successful career as a research scientist in the United States.